Color Difference Key effect

Note:

Though the color keying effects built into After
Effects can be useful for some purposes, you should try keying with
Keylight before attempting to use these built-in keying effects.
Some keying effects have been superseded by more modern effects
like Keylight.

The Color Difference Key effect creates transparency from opposite
starting points by dividing an image into two mattes, Matte Partial
A and Matte Partial B. Matte Partial B bases the transparency on
the specified key color, and Matte Partial A bases transparency
on areas of the image that don’t contain a second, different color.
By combining the two mattes into a third matte, called the alpha matte,
the Color Difference Key creates well-defined transparency values.

The Color Difference Key produces high-quality keying for all
well-lit footage items shot against a bluescreen or greenscreen
and works especially well with images that contain transparent or
semitransparent areas, such as smoke, shadows, or glass.

This effect works with 8-bpc and 16-bpc color.

Use the Color Difference Key effect

Select the layer that you want to make
partially transparent, and choose Effect > Keying > Color
Difference Key.

Note:

To use any of the eyedroppers in the Layer panel, choose
Color Difference Key from the View menu in the Layer panel.

In the Effect Controls panel, choose Matte Corrected
from the View menu. To view and compare the source image, both partial
mattes, and the final matte at the same time, choose [A, B, Matte]
Corrected, Final from the View menu. Other views available in the
View menu are described in step 10.

Select the appropriate key color: To key out a bluescreen,
use the default blue color. To key out a nonblue screen, select
a key color in one of the following ways:

Thumbnail eyedropper: Select and then click in the Composition panel or the original thumbnail image on an appropriate area.

Key Color eyedropper: Select and then click in the Composition or Layer panel on an appropriate area.

Key Color swatch: Click to select a color from the specified color space.

Note:

The eyedropper tools move the sliders accordingly. Use the sliders in step 9 to fine-tune the keying results.

Click the matte
button to display the final combined matte in the matte thumbnail.

Select the Black eyedropper, and then click inside the
matte thumbnail on the lightest area of black to specify transparent
regions. The transparency values in the thumbnail and Composition
panel are adjusted.

Select the White eyedropper, and then click inside the
matte thumbnail on the darkest area of white to specify opaque regions.
The opaque values in the thumbnail and the Composition panel are
adjusted.

To produce the best possible key, make
the black and white areas as different as you can so that the image
retains as many shades of gray as possible.

Select a matching accuracy from the Color Matching Accuracy
menu. Choose Faster unless you use a screen that isn’t a primary
color (red, blue, or yellow). For those screens, choose More Accurate,
which increases rendering time but produces better results.

To further adjust transparency values, repeat steps 5
and 6 for one or both of the partial mattes. Click the Partial Matte
B button or the Partial Matte A button to select a partial matte,
and then repeat the steps.

Adjust transparency values for each partial matte and
for the final matte by dragging one or more of the following sliders
in the Matte Controls section:

Black sliders adjust the transparency levels
of each matte. You can adjust the same levels using the Black eyedropper.

White sliders adjust the opaque levels of each matte.
You can adjust the same levels using the White eyedropper.

Gamma sliders control how closely the transparency
values follow a linear progression. At a value of 1 (the default),
the progression is linear. Other values produce nonlinear progressions
for particular adjustments or visual effects.

When adjusting individual mattes, choose from the View
menu to compare the mattes with and without adjustments:

Choose Uncorrected to view a matte without
adjustments.

Choose Corrected to view a matte with all adjustments.

Before closing the Effect Controls panel, select Final
Output from the View menu. Final Output must be selected for After
Effects to render the transparency.

To remove traces of reflected key color
from the image, apply Spill Suppressor using Better For Color Accuracy.
If the image still has a lot of color, apply the Simple Choker or
Matte Choker effect.

The Color Key effect keys out all image pixels that are similar
to a specified key color. This effect modifies only the alpha channel
of a layer.

This effect works with 8-bpc and 16-bpc color.

Key out a single color with the
Color Key effect

Select the layer that you want to make
partially transparent, and choose Effect > Keying > Color
Key.

In the Effect Controls panel, specify a key color in
one of two ways:

Click the Key Color swatch to open the
Color dialog box and specify a color.

Click the eyedropper, and then click a color on
the screen.

Drag the Color Tolerance slider to specify the range
of color to key out. Lower values key out a smaller range of colors
near the key color. Higher values key out a wider range of color.

Drag the Edge Thin slider to adjust the width of the
border of the keyed area. Positive values enlarge the mask, increasing
the transparent area. Negative values shrink the mask, decreasing
the transparent area.

Drag the Edge Feather slider to specify the softness
of the edge. Higher values create a softer edge but take longer
to render.

Color Range effect

Note:

Though the color keying effects built into After
Effects can be useful for some purposes, you should try keying with
Keylight before attempting to use these built-in keying effects.
Some keying effects have been superseded by more modern effects
like Keylight.

The Color Range effect creates transparency by keying out a specified
range of colors in either the Lab, YUV, or RGB color space. You
can use this key on screens that consist of more than one color
or on bluescreens or greenscreens that have been unevenly lit and
contain different shades of the same color.

Use the Color Range effect

Select the layer that you want to make
partially transparent, and choose Effect > Keying > Color
Range.

Choose Lab, YUV, or RGB from the Color Space menu. If
you have trouble isolating the subject using one color space, try
using a different one.

Select the Key Color eyedropper, and then click in the
matte thumbnail to select the area that corresponds to a color in
the Composition panel you want to make transparent. Typically, this
first color is the one that covers the largest area of the image.

Note:

To use the eyedroppers in the Layer panel, choose Color
Range from the View menu in the Layer panel.

Select the plus eyedropper, and then click other areas
in the matte thumbnail to add other colors or shades to the range
of colors keyed out for transparency.

Select the minus eyedropper, and then click areas in
the matte thumbnail to subtract other colors or shades from the
range of colors keyed out.

Drag the Fuzziness slider to soften the edges between
transparent and opaque regions.

Use the sliders in the Min and Max controls to fine-tune
the color range you selected with the plus and minus eyedroppers.
The L, Y, R sliders control the first component of the specified
color space; the a, U, G sliders control the second component; and
the b, V, B sliders control the third component. Drag the Min sliders
to fine-tune the beginning of the color range. Drag the Max sliders
to fine-tune the end of the color range.

Difference Matte effect

The Difference Matte effect creates transparency by
comparing a source layer with a difference layer, and then keying
out pixels in the source layer that match both the position and
color in the difference layer. Typically, it’s used to key out a static
background behind a moving object, which is then placed on a different background.
Often the difference layer is simply a frame of background footage (before
the moving object has entered the scene). For this reason, the Difference Matte
effect is best used for scenes that have been shot with a stationary
camera and an unmoving background.

Import the image file into After Effects, and add it
to the composition.

The imported image becomes the difference layer. Make sure
that its duration is at least as long as the duration of the source
layer.

Note:

If the shot doesn’t contain a full background frame,
you may be able to assemble the full background by combining parts
of several frames in After Effects or Photoshop. For example, you
can use the Clone Stamp tool to take a sample of the background
in one frame, and then paint the sample over part of the background
in another frame.

Turn off the display of the difference layer by clicking
the Video switch in the Timeline panel.

Make sure that the original source layer is selected,
and then choose Effect > Keying > Difference Matte.

In the Effect Controls panel, choose Final Output or
Matte Only from the View menu. (Use the Matte Only view to check
for holes in the transparency. To fill undesired holes after you
complete the keying process, see Close
a hole in a matte.)

Select the background file from the Difference Layer
menu.

If the difference layer isn’t the same size as the source
layer, choose one of the following controls from the If Layer Sizes
Differ menu:

Center

Places the difference layer in the center of the source
layer. If the difference layer is smaller than the source layer,
the rest of the layer fills with black.

Stretch To Fit

Stretches or shrinks the difference layer to the size
of the source layer. Background images may become distorted.

Adjust the Matching Tolerance slider to specify the amount
of transparency based on how closely colors must match between the
layers. Lower values produce less transparency; higher values produce
more transparency.

Adjust the Matching Softness slider to soften the edges
between transparent and opaque areas. Higher values make matched
pixels more transparent but don’t increase the number of matching
pixels.

If the matte still contains extraneous pixels, adjust
the Blur Before Difference slider. This slider suppresses noise
by slightly blurring both layers before the comparison is made.

Note:

The blurring occurs only for the comparison and doesn’t
blur final output.

Before closing the Effect Controls panel, make sure to
select Final Output from the View menu to ensure that After Effects
renders the transparency.

Extract effect

The Extract effect creates transparency by keying out
a specified brightness range, based on a histogram of a specified
channel. It’s best used to create transparency in an image shot
against a black or white background or against a background that
is dark or bright but consists of more than one color.

Note:

The controls for this effect are similar to the controls of
the Extract effect in Adobe Premiere Pro, but the purpose and results
of the effect are different.

This effect works with 8-bpc and 16-bpc color.

Use the Extract effect

In the Effect Controls panel, the Extract
effect displays a histogram for a channel specified in the Channel
menu. The histogram displays a representation of the brightness
levels in the layer, showing the relative number of pixels at each
level. From left to right, the histogram extends from the darkest
(a value of 0) to the lightest (a value of 255).

Using the
transparency control bar beneath the histogram, you can adjust the range
of pixels that are made transparent. The position and shape of the
bar in relation to the histogram determine transparency. Pixels
corresponding to the area covered by the bar remain opaque; pixels
corresponding to the areas not covered by the bar are made transparent.

Select the layer you want to make partially transparent,
and choose Effect > Keying > Extract.

If you are keying out bright or dark areas, choose Luminance
from the Channel menu. To create visual effects, choose Red, Green,
Blue, or Alpha.

Adjust the amount of transparency by dragging the transparency
control bar in the following ways:

Drag the upper right or upper left selection handles to adjust the length of the bar and to shorten or lengthen the transparency range. You can also adjust the length by moving the White Point and Black Point sliders. Values above the white point and below the black point are made transparent.

Drag the lower right or lower left selection handles to taper the bar. Tapering the bar on the left affects the softness of transparency in the darker areas of the image; tapering it on the right affects the softness in the lighter areas. You can also adjust the softness levels by adjusting White Softness (lighter areas) and Black Softness (darker areas).

Note:

To taper the edges of the transparency control bar, first shorten the transparency bar.

Inner/Outer Key effect

Note:

Though the color keying effects built into After
Effects can be useful for some purposes, you should try keying with
Keylight before attempting to use these built-in keying effects.
Some keying effects have been superseded by more modern effects
like Keylight.

The Inner/Outer Key effect isolates a foreground object from
its background.

This effect works with 8-bpc and 16-bpc color.

Use the Inner/Outer Key effect

To use the Inner/Outer key, create a mask
to define the inside and outside edge of the object you want to
isolate. The mask can be fairly rough—it doesn’t need to fit exactly
around the edges of the object.

In addition to masking a
soft-edged object from its background, Inner/Outer Key modifies
the colors around the border to remove contaminating background colors.
This color decontamination process determines the contribution of
the background to the color in each border pixel, and then removes
that contribution—thus removing the halo that can appear if a soft-edged
object is matted against a new background.

Select the border of the object that you want
to extract by doing one of the following:

Draw a single closed mask near the border of the object; then select the mask from the Foreground menu and leave the Background menu set to None. Adjust the Single Mask Highlight Radius to control the size of the border around this mask. (This method works well only on objects with simple edges.)

Draw two closed masks: an inner mask just inside the object, and an outer mask just outside the object. Make sure that any fuzzy or uncertain areas of the object lie within these two masks. Select the inner mask from the Foreground menu and the outer mask from the Background menu.

Note:

Make sure that the mask mode for all masks is set to None.

If you want, move the masks around to find the location
that provides the best results.

To extract more than one object, or to create a hole
in an object, draw additional masks and then select them from the
Additional Foreground and Additional Background menus. For example,
to key out a person’s hair blowing in the wind against a blue sky,
draw the inner mask inside the head, draw the outer mask around
the outside edge of the hair, and then draw an additional mask around
the gap in the hair where you can see sky. Select the additional mask
from the Additional Foreground menu to extract the gap and remove the
background image.

Create additional open or closed masks to clean up other
areas of the image, and then select them from the Cleanup Foreground
or Cleanup Background menu. Cleanup Foreground masks increase the
opacity along the mask; Cleanup Background masks decrease the opacity
along the mask. Use the Brush Radius and Brush Pressure options
to control the size and density of each stroke.

Note:

You can select the Background (outer) mask as a Cleanup
Background mask to clean up noise from the background portions of
the image.

Set Edge Thin to specify how much of the border of the
matte is affected by the key. A positive value moves the edge away
from the transparent region, increasing the transparent area; a
negative value moves the edge toward the transparent region and
increases the size of the foreground area.

Increase the Edge Feather values to soften edges of the
keyed area. High Edge Feather values take longer to render.

Specify the Edge Threshold, which is a soft cutoff for
removing low-opacity pixels that can cause unwanted noise in the
image background.

Select Invert Extraction to reverse the foreground and
background regions.

Set Blend With Original to specify the degree to which
the resulting extracted image blends with the original image.

Linear Color Key effect

Note:

Though the color keying effects built into After
Effects can be useful for some purposes, you should try keying with
Keylight before attempting to use these built-in keying effects.
Some keying effects have been superseded by more modern effects
like Keylight.

Linear keys create a range of transparency across
an image. A linear key compares each pixel in the image to the key
color you specify. If the color of a pixel closely matches the key
color, it becomes completely transparent. Pixels that don’t match
as well are made less transparent, and pixels that don’t match at
all remain opaque. The range of transparency values, therefore,
forms a linear progression.

Apply the Linear Color Key effect

In the Effect Controls panel, the Linear Color
Key effect displays two thumbnail images; the left thumbnail image
represents the unaltered source image, and the right thumbnail image
represents the view you’ve selected in the View menu.

You
can adjust the key color, the matching tolerance, and the matching
softness. The matching tolerance specifies how closely pixels must
match the key color before they start becoming transparent. The
matching softness controls the softness of edges between the image
and the key color.

You can also reapply this key to preserve
a color that was made transparent by the first application of the
key. For example, if you key out a medium-blue screen, you may lose
some or all of a light-blue piece of clothing your subject is wearing. You
can bring back the light-blue color by applying another instance
of the Linear Color Key and choosing Keep This Color from the Key
Operation menu.

In the Effect Controls panel, choose Key Colors from
the Key Operation menu.

Choose a color space from the Match Colors menu. In most
cases, use the default RGB setting. If you have trouble isolating
the subject using one color space, try using a different color space.

In the Effect Controls panel, choose Final Output from
the View menu. The view you choose appears in the right thumbnail
and in the Composition panel. To see other results, work in one
of the other views:

Source Only

Shows the original image without the key applied.

Matte Only

Shows the alpha channel matte. Use this view to check
for holes in the transparency. To fill undesired holes after you
complete the keying process, see Close
a hole in a matte.

Select a key color in one of the following ways:

Select the Thumbnail eyedropper, and then
click an appropriate area in the Composition panel or the original
thumbnail image.

Select the Key Color eyedropper, and then click
an appropriate area in the Composition or Layer panel.

To preview transparency for different colors, select
the Key Color eyedropper, hold down the Alt key (Windows) or Option
key (Mac OS), and move the pointer to different areas in the Composition
panel or the original thumbnail image. The transparency of the image
in the Composition panel changes as you move the pointer over different
colors or shades. Click to select the color.

Click the Key Color swatch to select a color from
the specified color space. The selected color becomes transparent.

note: The
eyedropper tools move the sliders accordingly. Use the sliders in
steps 6 and 7 to fine-tune the keying results. To use eyedroppers
in the Layer panel, choose Linear Color Key from the View menu in
the Layer panel.

Adjust matching tolerance in one of the following ways:

Select the Plus (+) or the Minus (-) eyedropper,
and then click a color in the left thumbnail image. The Plus eyedropper
adds the specified color to the key color range, increasing the
matching tolerance and the level of transparency. The Minus eyedropper
subtracts the specified color from the key color range, decreasing
the matching tolerance and the level of transparency.

Drag the matching tolerance slider. A value of 0
makes the entire image opaque; a value of 100 makes the entire image
transparent.

Drag the Matching Softness slider to soften the matching
tolerance by tapering the tolerance value. Typically, values under
20% produce the best results.

Before closing the Effect Controls panel, make sure to
select Final Output from the View menu to ensure that After Effects
renders the transparency.

Preserve a color after applying
Linear Color Key

In the Effect Controls panel or Timeline
panel, turn off any current instances of keys or matte effects by
deselecting the Effect option to the left of the key name or tool
name. Deselecting the option causes the original image to appear
in the Composition panel so that you can select a color to preserve.

Choose Effect > Keying > Linear Color Key. A second
set of Linear Color Key controls appears in the Effect Controls
panel below the first set.

In the Effect Controls panel, choose Keep Colors from
the Key Operation menu.

Select the color you want to keep.

In the first application of the Linear Color Key effect,
choose Final Output from the View menu in the Effect Controls panel,
and then turn other instances of the Linear Color Key effect back
on to examine the transparency. You may need to adjust colors or
reapply the key a third time to get the results you need.

Luma Key effect

Note:

Starting with the October 2013 release of After Effects CC, the Luma Key effect has been moved to the Obsolete effects category and users are recommended to use other effects such as the Keylight effect.

The Luma Key effect keys out all the regions of a layer with
a specified luminance or brightness. The quality setting of the
layer doesn’t influence the Luma Key effect.

Use this effect if the object from which you want to create a
matte has a greatly different luminance value than its background.
For example, if you want to create a matte for musical notes on
a white background, you can key out the brighter values; the dark
musical notes become the only opaque areas.

This effect works with 8-bpc and 16-bpc color.

White background of original (upper-left and lower-left) is
removed using Luma Key and composited over underlying layer (lower-right).

Key out a luminance value with
the Luma Key effect

Select the layer that you want to make
partially transparent, and choose Effect > Keying > Luma Key.

Select a Key Type to specify the range to be keyed out.

Drag the Threshold slider in the Effect Controls panel
to set the luminance value you want the matte to be based on.

Drag the Tolerance slider to specify the range of values
to be keyed out. Lower values key out a smaller range of values
near the threshold. Higher values key out a wider range of values.

Drag the Edge Thin slider to adjust the width of the
border of the keyed area. Positive values make the mask grow, increasing
the transparent area. Negative values shrink the mask.

Drag the Edge Feather slider to specify the softness
of the edge. Higher values create a softer edge but take longer
to render.

Spill Suppressor effect

Note:

Starting with the June 2014 release of After Effects CC, the Spill Suppressor effect has been moved to the Obsolete effects category and users are recommended to use the Advanced Spill Suppressor effect.

The Spill Suppressor effect removes traces of the key color from an image with a screen that’s already been keyed out. Typically, the Spill Suppressor is used to remove key color spills from the edges of an image. Spills are caused by light reflecting off the screen and onto the subject.

If you’re not satisfied with the results from using the Spill Suppressor, try applying the Hue/Saturation effect to a layer after keying, and then decrease the saturation value to de-emphasize the key color.

Use the Spill Suppressor effect

If you already keyed out the color with a key in the Effect Controls panel, click the Color To Suppress eyedropper, and then click the screen color in the Key Color swatch for the key.

In Spill Suppressor, click the Key Color swatch and choose a color from the color wheel.

Note: To use the eyedropper in the Layer panel, choose Spill Suppressor from the View menu in the Layer panel.

From the Color Accuracy menu, choose Faster to suppress blue, green, or red. Choose Better to suppress other colors, because After Effects may need to analyze the colors more carefully to produce accurate transparency. The Better option may increase rendering time.

Key Cleaner and Advanced Spill Suppressor effect

Key Cleaner effect

The Key Cleaner effect recovers alpha-channel detail from a scene keyed by a typical keying effect, including recovering detail lost due to compression artifacts.

If you see that unwanted semi-transparency effects have crept in along edges that should be sharp, use an effect mask (with a little mask feather) to restrict the Key Cleaner effect to the intended area.

Advanced Spill Suppressor effect

The Advanced Spill Suppressor effect removes color spill on a foreground subject from a colored background used for color keying.

The Advanced Spill Suppressor effect has two methods for spill suppression:

Ultra - The Ultra method is based on the spill suppression in the Ultra Key effect in Premiere Pro. See the Ultra Key section in Premiere Pro for details about the Ultra Key.

An easy way of applying these effects is by using the Keylight + Key Cleaner + Spill Suppressor animation preset.

Note:

Starting with the June 2014 release of After Effects CC, the Spill Suppressor effect has been moved to the Obsolete effects category and users are recommended to use the Advanced Spill Suppressor effect.

Keylight effect

After Effects includes several built-in keying effects,
as well as the Academy Award–winning Keylight effect, which excels
at professional-quality color keying. For information on the Keylight
effect, see its documentation in the folder in which the Keylight
plug-in is installed. (See Plug-ins.)

The Key Color property is already linked with an expression to the Keylight effect's Screen Colour property, so you don't need to change it unless you want to use a different color for the despill process. To use a different color for the despill process, just disable or remove the Keylight expression.

Follow the steps below to apply the Keylight effect with the Key Cleaner and Advanced Spill Suppressor effect:

Use the Keylight + Key Cleaner + Advanced Spill Suppressor animation preset (in the Image-Utlities folder inder Animation Presets) to apply the three effects in order to the layer.The Advanced Spill Suppressor effect is turned off by default to allow you to sample the key color in the Keylight effect or if the footage does not have any color spill to be removed.

Use the Keylight effect's Screen Colour eyedropper to sample the key color from the layer in the Composition panel. Adjust other Keylight effect settings as you normally would to get the best results.

Turn on the effect switch for the Advanced Spill Suppressor effect to remove color spill from the scene, if required.

If you see unwanted semitransparency along edges that should be sharp, use an effect mask (with a little bit of mask feather) to restrict Key Cleaner to the intended area.

Learn Tutorial

Watch this video to learn how to get better keying results from compressed or badly shot green-screen footage with the new Key Cleaner effect and remove color spill with the Advanced Spill Suppressor controls.